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    <h1 class="title">DBNull Class</h1>

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            <strong>Java 1.6</strong>
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<p>

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        <p>Represents a nonexistent value. This class cannot be inherited.</p>
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        <a href="http://msdn.microsoft.com/en-us/library/system.object">System<span>.</span>Object</a>
        <br>&nbsp;&nbsp;<span class="selflink"
            >System<span
            xmlns="">.</span>DBNull</span><br></div>
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<p>

</p> <strong>Namespace:</strong>
&nbsp;<a href="#">System</a><br>

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                    <div style="color:Black;"><pre>[SerializableAttribute]
[ComVisibleAttribute(<span style="color:Blue;">true</span>)]
<span style="color:Blue;">public</span>&nbsp;<span style="color:Blue;">sealed</span>&nbsp;<span style="color:Blue;">class</span>&nbsp;DBNull : ISerializable, 
	IConvertible
</pre>
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<p>The <span class="selflink">DBNull</span> type exposes the following members.</p>

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                    <img id="pubmethod" alt="Public method"
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                         class="cl_IC91302">
                    <img id="xna" alt="Supported by the XNA Framework"
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                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/bsc2ak47">Equals(Object)</a>
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                <td>
                    <span>Determines whether the specified <span><a
                            href="http://msdn.microsoft.com/en-us/library/system.object">Object</a></span> is equal to the current <span><a
                            href="http://msdn.microsoft.com/en-us/library/system.object">Object</a></span>.</span>
                    (Inherited from <a href="http://msdn.microsoft.com/en-us/library/system.object">Object</a>.)
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                    <img id="protmethod" alt="Protected method"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Protected method"
                         xmlns="" class="cl_IC155188">
                    <img id="xna" alt="Supported by the XNA Framework"
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                </td>
                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/system.object.finalize">Finalize</a>
                </td>
                <td>
                    <span>Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.</span>
                    (Inherited from <a href="http://msdn.microsoft.com/en-us/library/system.object">Object</a>.)
                </td>
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                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/system.object.gethashcode">GetHashCode</a>
                </td>
                <td>
                    <span>Serves as a hash function for a particular type. </span> (Inherited from <a
                        href="http://msdn.microsoft.com/en-us/library/system.object">Object</a>.)
                </td>
            </tr>
            <tr data="public;declared;">

                <td>
                    <img id="pubmethod" alt="Public method"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Public method" xmlns=""
                         class="cl_IC91302">
                </td>
                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/system.dbnull.getobjectdata">GetObjectData</a>
                </td>
                <td>
                    <span>Implements the <span><a
                            href="http://msdn.microsoft.com/en-us/library/system.runtime.serialization.iserializable">ISerializable</a></span> interface and returns the data needed to serialize the <span><span
                            class="selflink">DBNull</span></span> object.</span>
                </td>
            </tr>
            <tr data="public;inherited;xnafw;">

                <td>
                    <img id="pubmethod" alt="Public method"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Public method" xmlns=""
                         class="cl_IC91302">
                    <img id="xna" alt="Supported by the XNA Framework"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
                         title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
                </td>
                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/system.object.gettype">GetType</a>
                </td>
                <td>
                    <span>Gets the <span><a href="http://msdn.microsoft.com/en-us/library/system.type">Type</a></span> of the current instance.</span>
                    (Inherited from <a href="http://msdn.microsoft.com/en-us/library/system.object">Object</a>.)
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                    <img id="pubmethod" alt="Public method"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Public method" xmlns=""
                         class="cl_IC91302">
                    <img id="xna" alt="Supported by the XNA Framework"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
                         title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
                </td>
                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/system.dbnull.gettypecode">GetTypeCode</a>
                </td>
                <td>
                    <span>Gets the <span><a href="http://msdn.microsoft.com/en-us/library/system.typecode">TypeCode</a></span> value for <span><span
                            class="selflink">DBNull</span></span>.</span>
                </td>
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                <td>
                    <img id="protmethod" alt="Protected method"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Protected method"
                         xmlns="" class="cl_IC155188">
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                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/system.object.memberwiseclone">MemberwiseClone</a>
                </td>
                <td>
                    <span>Creates a shallow copy of the current <span><a
                            href="http://msdn.microsoft.com/en-us/library/system.object">Object</a></span>.</span>
                    (Inherited from <a href="http://msdn.microsoft.com/en-us/library/system.object">Object</a>.)
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                    <img id="pubmethod" alt="Public method"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Public method" xmlns=""
                         class="cl_IC91302">
                    <img id="xna" alt="Supported by the XNA Framework"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
                         title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
                </td>
                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/zkbzs85t">ToString<span xmlns="">()</span></a>
                </td>
                <td>
                    <span>Returns an empty string (<span><a
                            href="http://msdn.microsoft.com/en-us/library/system.string.empty">String<span
                            xmlns="">.</span>Empty</a></span>).</span> (Overrides <a
                        href="http://msdn.microsoft.com/en-us/library/system.object.tostring">Object<span
                        xmlns="">.</span>ToString<span xmlns="">()</span></a>.)
                </td>
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                    <img id="pubmethod" alt="Public method"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Public method" xmlns=""
                         class="cl_IC91302">
                    <img id="xna" alt="Supported by the XNA Framework"
                         src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
                         title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
                </td>
                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/z09h5zw4">ToString(IFormatProvider)</a>
                </td>
                <td>
                    <span>Returns an empty string using the specified <span><a
                            href="http://msdn.microsoft.com/en-us/library/system.iformatprovider">System<span
                            xmlns="">.</span>IFormatProvider</a></span>.</span>
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                <td>
                    <a href="http://msdn.microsoft.com/en-us/library/system.dbnull.value">Value</a>
                </td>
                <td>
                    <span>Represents the sole instance of the <span><span
                            class="selflink">DBNull</span></span> class.</span>
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        <img id="privmethod" alt="Private method"
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             xmlns="" class="cl_IC6709">
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    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb356975">IConvertible<span xmlns="">.</span>ToBoolean</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
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        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb342489">IConvertible<span xmlns="">.</span>ToByte</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
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    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb298422">IConvertible<span xmlns="">.</span>ToChar</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
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    <td>
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             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb292317">IConvertible<span xmlns="">.</span>ToDateTime</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
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    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb361170">IConvertible<span xmlns="">.</span>ToDecimal</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
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    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb357599">IConvertible<span xmlns="">.</span>ToDouble</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
<tr data="explicit;declared;xnafw;">

    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb301549">IConvertible<span xmlns="">.</span>ToInt16</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
<tr data="explicit;declared;xnafw;">

    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb343198">IConvertible<span xmlns="">.</span>ToInt32</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
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        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb347253">IConvertible<span xmlns="">.</span>ToInt64</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
<tr data="explicit;declared;xnafw;">

    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb337393">IConvertible<span xmlns="">.</span>ToSByte</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
<tr data="explicit;declared;xnafw;">

    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb298221">IConvertible<span xmlns="">.</span>ToSingle</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
<tr data="explicit;declared;xnafw;">

    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb337734">IConvertible<span xmlns="">.</span>ToType</a>
    </td>
    <td>Infrastructure. <span>Converts the current <span><span class="selflink">DBNull</span></span> object to the specified type.</span>
    </td>
</tr>
<tr data="explicit;declared;xnafw;">

    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb347557">IConvertible<span xmlns="">.</span>ToUInt16</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
<tr data="explicit;declared;xnafw;">

    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb347553">IConvertible<span xmlns="">.</span>ToUInt32</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
<tr data="explicit;declared;xnafw;">

    <td>
        <img id="pubinterface" alt="Explicit interface implemetation"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Explicit interface implemetation" xmlns="" class="cl_IC141795">
        <img id="privmethod" alt="Private method"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif" title="Private method"
             xmlns="" class="cl_IC6709">
        <img id="xna" alt="Supported by the XNA Framework"
             src="http://i.msdn.microsoft.com/areas/global/content/clear.gif"
             title="Supported by the XNA Framework" xmlns="" class="cl_IC37116">
    </td>
    <td>
        <a href="http://msdn.microsoft.com/en-us/library/bb302206">IConvertible<span xmlns="">.</span>ToUInt64</a>
    </td>
    <td>Infrastructure. <span>This conversion is not supported. Attempting to make this conversion throws an <span><a
            href="http://msdn.microsoft.com/en-us/library/system.invalidcastexception">InvalidCastException</a></span>.</span>
    </td>
</tr>
</tbody>
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    <div class="sectionblock"><a id="remarksToggle">

    </a>

        <p>The <span><span class="selflink">DBNull</span></span> class represents a
            nonexistent value. In a database, for example, a column in a row of a table might not contain any data
            whatsoever. That is, the column is considered to not exist at all instead of merely not having a value. A
            <span><span class="selflink">DBNull</span></span> object represents the nonexistent column. Additionally,
            COM interop uses the <span><span class="selflink">DBNull</span></span> class to distinguish between a
            VT_NULL variant, which indicates a nonexistent value, and a VT_EMPTY variant, which indicates an unspecified
            value.</p>

        <p>The <span><span class="selflink">DBNull</span></span> type is a
            singleton class, which means only one <span><span class="selflink">DBNull</span></span> object exists. The
            <span><a href="http://msdn.microsoft.com/en-us/library/system.dbnull.value">DBNull<span xmlns="">.</span>Value</a></span>
            member represents the sole <span><span class="selflink">DBNull</span></span> object. <span><a
                    href="http://msdn.microsoft.com/en-us/library/system.dbnull.value">DBNull<span xmlns="">.</span>Value</a></span>
            can be used to explicitly assign a nonexistent value to a database field, although most ADO.NET data
            providers automatically assign values of <span><span class="selflink">DBNull</span></span> when a field does
            not have a valid value. You can determine whether a value retrieved from a database field is a <span><span
                    class="selflink">DBNull</span></span> value by passing the value of that field to the <span><span
                    class="input">DBNull.Value.Equals</span></span> method. However, some languages and database objects
            supply methods that make it easier to determine whether the value of a database field is <span><a
                    href="http://msdn.microsoft.com/en-us/library/system.dbnull.value">DBNull<span xmlns="">.</span>Value</a></span>.
            These include the Visual Basic <span><span class="input">IsDBNull</span></span> function, the <span><a
                    href="http://msdn.microsoft.com/en-us/library/system.convert.isdbnull">Convert<span
                    xmlns="">.</span>IsDBNull</a></span> method, the <span><a
                    href="http://msdn.microsoft.com/en-us/library/system.data.datatablereader.isdbnull">DataTableReader<span
                    xmlns="">.</span>IsDBNull</a></span> method, and the <span><a
                    href="http://msdn.microsoft.com/en-us/library/system.data.idatarecord.isdbnull">IDataRecord<span
                    xmlns="">.</span>IsDBNull</a></span> method.</p>

        <p>Do not confuse the notion of <span><span class="input"><span xmlns="">null</span></span><span
                xmlns=""></span></span> in an object-oriented programming language with a <span><span class="selflink">DBNull</span></span>
            object. In an object-oriented programming language, <span><span class="input"><span
                    xmlns="">null</span></span><span xmlns=""></span></span> means the absence of a reference to an
            object. <span><span class="selflink">DBNull</span></span> represents an uninitialized variant or nonexistent
            database column.</p>
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    <div class="sectionblock"><a id="exampleToggle">

    </a>

        <p>The following example calls the <span><span class="input">DBNull.Value.Equals</span></span>
            method to determine whether a database field in a contacts database has a valid value. If it does, the field
            value is appended to the string output in a label.</p>

        <div>

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                         dir="ltr"><a>C#</a></div>
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                         class="codeSnippetContainerCode" dir="ltr">
                        <div style="color:Black;"><pre><span style="color:Blue;">private</span>&nbsp;<span
                                style="color:Blue;">void</span> OutputLabels(DataTable dt)
{
   <span style="color:Blue;">string</span> label; 

   <span style="color:Green;">// Iterate rows of table&nbsp;</span>
   <span style="color:Blue;">foreach</span> (DataRow row <span style="color:Blue;">in</span> dt.Rows)
   {
      <span style="color:Blue;">int</span> labelLen;
      label = String.Empty;
      label += AddFieldValue(label, row, <span style="color:#A31515;">"Title"</span>);
      label += AddFieldValue(label, row, <span style="color:#A31515;">"FirstName"</span>);
      label += AddFieldValue(label, row, <span style="color:#A31515;">"MiddleInitial"</span>);
      label += AddFieldValue(label, row, <span style="color:#A31515;">"LastName"</span>);
      label += AddFieldValue(label, row, <span style="color:#A31515;">"Suffix"</span>);
      label += <span style="color:#A31515;">"\n"</span>;
      label += AddFieldValue(label, row, <span style="color:#A31515;">"Address1"</span>);
      label += AddFieldValue(label, row, <span style="color:#A31515;">"AptNo"</span>);
      label += <span style="color:#A31515;">"\n"</span>;
      labelLen = label.Length;
      label += AddFieldValue(label, row, <span style="color:#A31515;">"Address2"</span>);
      <span style="color:Blue;">if</span> (label.Length != labelLen)
         label += <span style="color:#A31515;">"\n"</span>;
      label += AddFieldValue(label, row, <span style="color:#A31515;">"City"</span>);
      label += AddFieldValue(label, row, <span style="color:#A31515;">"State"</span>);
      label += AddFieldValue(label, row, <span style="color:#A31515;">"Zip"</span>);
      Console.WriteLine(label);
      Console.WriteLine();
   }
}

<span style="color:Blue;">private</span>&nbsp;<span style="color:Blue;">string</span> AddFieldValue(<span
                                    style="color:Blue;">string</span> label, DataRow row, 
                             <span style="color:Blue;">string</span> fieldName) 
{                                
   <span style="color:Blue;">if</span> (! DBNull.Value.Equals(row[fieldName])) 
      <span style="color:Blue;">return</span> (<span style="color:Blue;">string</span>) row[fieldName] + <span
                                    style="color:#A31515;">" "</span>;
   <span style="color:Blue;">else</span>&nbsp;
      <span style="color:Blue;">return</span> String.Empty;
}
</pre>
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            <!--later; Itanium not supported)</p>-->

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    <div class="sectionblock"><a id="threadSafetyToggle">

    </a>Any public <span class="input">static</span> (<span class="input"
            >Shared</span>
        in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread
        safe.
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